1. Field of the Invention
The present invention relates to a solid state imaging apparatus, and more specifically, a solid state imaging apparatus operable in an interlaced scanning or non-interlaced scanning schema. Particularly, the solid state imaging apparatus in accordance with the present invention is usable in the case of using a charge-coupled device (CCD) type of solid state imager.
2. Description of Related Art
With recent advancement in technology, a solid state imager has been miniaturized more and more, and resolution of the solid state imager has been increased more and more. In addition, sensitivity such as S/N ratio has been steadily improved with improvement in on-chip amplifiers and signal processing performed by peripheral circuits. However, realization of increased resolution cannot avoid decrease of an area of each photoelectric conversion cell and decrease of a width of a vertical transfer register, and also, a dynamic range of an output signal has been inevitably decreased.
Most of conventional solid state imagers have been designed on the premise of a 2:1 interlaced scanning in accordance with a current television format. Therefore, each vertical transfer register has been constructed so that one independent potential well is provided for each pair of photoelectric conversion cells arranged adjacent to each other in a vertical direction. On the other hand, a non-interlaced scanning has been proposed in an extended definition TV (EDTV) which is now considered for improvement of a picture quality in a television broadcasting. In this case, one independent potential well is required for each one photoelectric conversion cell.
As mentioned above, in the solid state imagers, a charge amount transferred in the vertical transfer register has a tendency to decrease more and more. Therefore, the width of the vertical transfer register has been now designed in consideration of balance between sensitivity and a maximum output of the photoelectric conversion cell. As a result, the degree of freedom in design has become small, and the dynamic range of the solid state imager has been greatly restricted.